Less than a month remains in the regular season, and the playoff races remain tight as rush hour traffic on the 405. Here’s what you need to know about Round 31, which finished with an usually busy Sunday foursome of matches.

The big results

So many, really, considering playoff races in each conference that simply refuse to yield all that fascinating congestion.

Tim Cahill’s second half equalizer gave the Red Bulls a useful 1-1 draw in Seattle, where the Sounders fumbled away numerous chances to put away a side missing its its top attacker (Thierry Henry) and top defender (Jamison Olave). Seattle retains the inside track on Supporters Shield (based on the number of games remaining), but it was a result the Red Bulls can take pride in.

Columbus’ surprising 4-2 win in Dallas, the Crew’s second consecutive road win, was massive in the playoff jostle. The Crew looked so close to dead a few weeks ago, but a string of impressive results has kept interim coach Brian Bliss and his troops among the post-season hopefuls. Oh, and it was also was probably a knockout punch for FC Dallas, now five points out of the race.

The “controversial” decision – that wasn’t a bit controversial

LA Galaxy players and coaches, reinforcing that sense of entitlement that has become so familiar through the Bruce Arena years in Southern California, were absolutely apoplectic about a late Robbie Keane goal that was waved off, judged offside, in Portland. And it was a swell strike, a crisp near-post header off Landon Donovan’s precision free kick service.

But replays demonstrated that Keane was offside, just as the referee’s assistant correctly ruled.

We get on the men in the middle a lot on this site, so it’s only fair to point out when they get a very close, and quite important decision absolutely correct. Job well done, guys. Here’s that one:

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The most surprising result

Philadelphia was perhaps one more big punch from being knocked plum out of this fight, having fallen from second all the way to seventh. So going into Sporting Kansas City and coming away with a 1-0 win (over a team still thinking “Supporters Shield”) was easily the big upset of Round 31.

The most impressive result

It’s not like Real Salt Lake had much of a choice, surely needing to trust the reserves Saturday night in Vancouver. With the U.S. Open Cup final coming up Tuesday at Rio Tinto Stadium, RSL manager Jason Kreis filled his lineup at BC Place with young talent and backups – and what a night it was for his club when the reserves came through with a 1-0 win.

So the starters are rested for Tuesday’s huge match, the team remained up near the top of the West and Vancouver … well, Martin Rennie’s team is left to rue the squandered opportunity.

The top tactical change

A goal down, Houston got aggressive on the road, subtracting a defender in favor of an extra attacker in a 3-5-2 look. It paid off quickly as Will Bruin found goal for the equalizer in a 1-1 draw at New England. By splitting the points, not only did Houston keep the inside track on a playoff spot (the Dynamo schedule ahead is favorable compared to other Eastern Conference playoff chasers), but Dominic Kinnear’s team simultaneously prevented one of its pursuers from picking up two additional points.

Saturday’s match at Toyota Park outside Chicago didn’t just have playoff implications (like so many of Week 31 contests did), it also featured the league’s top two scorers. Montreal’s Marco Di Vaio scored once, but top pursuer Mike Magee from Chicago slotted home a pair. So Magee cut the gap to one. The update list of MLS top scorers is on the right.

Caleb Porters great choice

Ryan Johnson has been the Portland Timbers first-choice striker for most of the season. So the decision by manager Caleb Porter to give young Argentine Maximiliano Urruti the start in such a meaningful match Sunday afternoon at rainy, wind-swept Jeld-Wen Field was a bit of a gamble. Urruti, 22, made his manager look good, scoring the game’s only goal in the 1-0 result mentioned above.

The weekend’s huge boo-boo

Montreal’s attackers eventually bailed out their goalkeeper, but it looked for a while like Troy Perkins embarrassing mistake in the back was going to be the difference in an important Eastern Conference clash.

Perkins, Montreal’s veteran goalkeeper, tried to get a little cute and evade Magee inside his own penalty area. Big. Mistake.

Yes, Magee fouled the Impact goalkeeper, but that hardly excuses such a blunder, a “howler” in the vernacular. Montreal’s subsequent equalizer made the final 2-2 at Toyota Park. Here’s the play:

HOUSTON (AP) Stanford got off to a rough start this year, but rebounded in a season where everyone wanted to take the Cardinal down to make it back to the College Cup.

After winning the first national championship in program history last season, No. 5 Stanford continues its title defense in the second semifinal on Friday night against No. 9 North Carolinas. In the first semifinal, No. 2 Wake Forest faces undefeated No. 6 Denver.

Stanford had with three ties and a loss in its first six games before winning 13 of its next 16 games to win a third straight Pac-12 championship and return to the College Cup.

“I think it was kind of a wakeup call seeing how hard we were going to get played and I think we adapted to that as the season progressed,” said defender Tomas Hilliard-Arce, who was named Pac-12 Defensive Player of the Year last month.

Stanford hopes to become the first team since Indiana in 2003-04 to win consecutive national championships. Coach Jeremy Gunn’s team is the first to return to the College Cup the season after winning the national championship since Wake Forest returned in 2008 after winning it all in 2007.

Stanford lost some key players from last season, including MLS Rookie of the Year and the reigning Hermann Trophy winner Jordan Morris. But it returns six starters from last season’s team. Five of those players were named to the All-Pac-12 first team last month, and one was on the second team.

“We had some great players leave after last year and I think some people wanted to write us off this year,” Gunn said.

Stanford is led by Co-Pac-12 player of the year Foster Langsdorf. The junior forward has led the team’s attack this season, scoring 15 goals, including one in each of Stanford’s three tournament games. In their 10 Pac-12 games, Langsdorf scored 12 goals.

North Carolina comes to Houston for its first College Cup appearance since winning a national championship in 2011. The Tar Heels also reached the national semifinals in 2009-10.

Some things to know about the College Cup.

H-TOWN CONNECTION: The Tar Heels come to Houston with many connections to the area. Three Houston Dynamo players, defenders Jalil Anibaba and Sheanon Williams and goalkeeper Tyler Deric, played at North Carolina, while head coach Carlos Somoano is from nearby Seabrook, Texas. The Tar Heels leading scorer, Tucker Hume, said players from the Dynamo have reached out to them and that they’ll be at Friday’s game.

“My formative soccer years and experiences were done right here in Houston,” Somoano said. “So for me it’s very special to be back here.”

YOUTH MOVEMENT: After losing key players from last season, including three who were selected in the top 12 of the MLS SuperDraft, North Carolina has had to rely on its youth in 2016. The Tar Heels have 12 players who have appeared in all 20 games this season, six of whom are either freshmen or sophomores. Sophomore forward Nils Bruening leads the team in goals with eight, while redshirt sophomore goalkeeper James Pyle has allowed just 10 goals this season.

“They’ve been a bit of a revelation for us,” Somoano said. “It’s just fascinating to see how they evolve through the year. They’re not the same players now than they were in August.”

FAMILIAR FACES: Denver head coach Jamie Franks and Wake Forest’s Bobby Muuss have plenty of history. Muuss was an assistant coach for the Demon Deacons during Franks’ freshman season in Winston-Salem and was the coach at Denver from 2007-14, with Franks serving as his assistant for three seasons. When Muuss took over at Wake Forest before the 2015 season, Franks took his place at Denver.

“I love Wake Forest . but at the end of the day, these are my boys,” Franks said. “These are my kids, and Wake Forest is standing in our way.

WAKE EYES REDEMPTION: Last season, Wake Forest was the No. 1 team in the country with a 17-2-2 record before falling in the quarterfinals to the eventual national champions Stanford in overtime. This season, the Demon Deacons enter the College Cup with an 18-2-3 mark with a pair of shutouts in wins over Coastal Carolina and Virginia Tech.

DOMINANCE REWARDED: Since Franks took over as the Denver head coach, the Pioneers have lost just one game, a defeat to SMU that ended the 2015 season. The team feels its 35-1-6 record under Franks it has not received enough credit, mostly because the Pioneers play in the Summit League. This is Denver’s first appearance in the College Cup and the players are embracing their underdog role.

“It’s more a historical thing than an actual thing because no one in our locker room is surprised to be here, we expected to be here,” sophomore forward Andre Shinyashiki said.

LONDON (AP) Police overseeing the sex abuse scandal in British soccer say 83 potential suspects have been identified and linked to 98 clubs.

Officers across the country are sifting through 639 referrals received by both police and a helpline established last month when former players started going public to say they were abused by coaches while in youth teams.